Liquid and gaseous hydrocarbons for energy use are in short supply throughout the world. Therefore, the prior art has attempted to produce liquid and gaseous carbonaceous material (e.g. hydrocarbons) from solid carbonaceous particles which also contains inorganic matter. In general, the prior art pyrolyzes the solid carbonaceous particles containing inorganic matter to produce carbonaceous liquids and gases which can then be used as energy sources.
One method suggested by the prior art is to pyrolyze the solid carbonaceous material in a fluidized bed in which the heat for the pyrolysis is supplied by heat-carrying bodies wherein the heat-carrying bodies are heated by combusting the residual carbon contained in the spent pyrolyzed solid carbonaceous particles. This method has some advantages over other pyrolysis methods in that fluid bed pyrolysis using heat-carrying bodies which have been reheated by combustion enables a more efficient use of the available energy in the solid carbonaceous particles. However, fluidized bed pyrolysis, as taught by the prior art, suffers certain disadvantages, one of the main ones being that the fluidization and pyrolysis are not uniform causing hot spots, etc. in the pyrolysis zone. In addition, in the prior art method utilizing a fluidized pyrolysis zone the spent carbonaceous particles are not efficiently combusted thereby wasting energy. This is particularly true when the solid carbonaceous particles contain mineral carbonates, such as dolomite and limestone, which decompose endothermically thereby causing a waste of heat.
Among prior art patents showing a fluid bed pyrolysis zone is U.S. Pat. No. 2,618,589. This patent discloses pyrolyzing solid carbonaceous particles in a fluidized bed using a two stage retort with a middle perforated screen between the two stages to prevent fines in the lower stage of the retort from entering the upper stage of the retort. Because of the rectangular shape of the pyrolysis stages (when viewed in sectional elevational view, as shown in FIGS. 1-3 of the patent), this patent suffers from a serious disadvantage in that fluidization and pyrolysis are not uniform. Moreover, although this patent does disclose a separate combustion zone for reheating the spent solid carbonaceous particles by burning the residual carbon in said spent carbonaceous particles, the combustion zone is not efficient and will cause the mineral carbonates in the spent carbonaceous particles to decompose endothermically.
From the foregoing it is readily apparent that it is a desideratum in the art to provide uniform pyrolysis and fluidization of solid carbonaceous material to recover carbonaceous liquids and gases therefrom and to do this economically and efficiently.